What Internxt does well
Internxt is, in most respects, exactly the kind of product this site argues for. It is based in Valencia, Spain, operates under GDPR, and stores files across European data centres. Its architecture is zero-knowledge with AES-256: files are encrypted on your device before upload, and Internxt cannot read them. That is a checkable claim rather than an asserted one, and how to verify Internxt's zero-knowledge encryption sets out the checks. Its client apps — desktop, web, mobile and CLI — are open source: the web and mobile apps under AGPL-3.0, the desktop app, SDK and CLI under MIT. And it has already gone further than many: Internxt has had its web, mobile and desktop apps and cloud services penetration-tested by Securitum, a European security firm.
It has also adopted post-quantum cryptography, with a specific scope: Internxt's post-quantum layer is a hybrid of Kyber-512 (NIST security category 1, from a pre-standard round-3 library) and elliptic-curve keys, and it wraps account and sharing keys rather than the per-file content keys. Internxt's newer Mail product uses ML-KEM-768.
So this is not the usual "incumbent that gets the architecture wrong." Internxt gets most of it right. The honest comparison below is narrow, and we will keep it that way.
Why people look for an alternative
Because Internxt and ShieldFive agree on so much — EU hosting, open source, zero-knowledge AES-256, and post-quantum encryption in principle — the reasons to compare them are specific:
- A higher post-quantum security category. They want the largest standardized post-quantum margin, not the smallest, for files with a long confidentiality lifetime.
- More free space. They want a larger free quota to evaluate the product properly, or to keep.
These are differences of degree, not of architecture. If neither matters to you, Internxt is a genuinely good answer and you should treat it as one.
ShieldFive: implementation and limits
ShieldFive encrypts files on the device before upload. Your password never reaches our servers: the browser turns it into a separate login value with Argon2id and sends only that, and the key that opens the vault is derived separately and stays on the device. The app code is delivered by ShieldFive, so the client you are served remains part of the trust boundary; client-side encryption does not mean that ShieldFive is technically unable to decrypt files.
Web uploads default to ML-KEM-1024/XChaCha20-Poly1305, with an AES-256-GCM fallback. Android also defaults to the hybrid format, with the same AES-256-GCM fallback, and reads both formats. This is not post-quantum hybrid encryption on every client or every upload.
Encrypted data is stored in the EU. The crypto core is open under Apache-2.0; the applications are closed-source and no external security audit has been completed. Review the security model and current plans before choosing.
ShieldFive vs Internxt at a glance
| Capability | ShieldFive | Internxt |
|---|---|---|
| Post-quantum strength | Hybrid default on web and Android, AES-GCM fallback | Hybrid Kyber-512 (NIST level 1, pre-FIPS) on account and sharing keys, not file keys |
| File-content cipher | Web and Android: hybrid/AES-GCM | AES-256 |
| EU data residency | Yes | Yes (Spain / EU data centres) |
| Zero-knowledge | Client-side; authentication trust applies | Yes |
| Open-source | Crypto core (Apache-2.0) | Yes — clients (AGPL-3.0 / MIT) |
Comparison reflects each vendor's public documentation as of 22 September 2026 and is updated as products change.
Where Internxt is ahead, honestly
A fair comparison has to run both ways, and with a competitor this close, it especially has to. Here is where Internxt is the stronger choice today.
A completed independent assessment. This is the big one. Internxt has had its applications and cloud services penetration-tested by Securitum, a European security firm, and it holds an independently verified ISO/IEC 27001:2022 certification. ShieldFive's crypto core is open and readable, but it has not yet completed an external audit or any comparable certification — that work is planned, not done. If a completed, independent assessment is a hard requirement right now, Internxt is ahead, and it would be dishonest to imply otherwise.
Track record. Internxt has shipped this product, with this architecture, for longer than ShieldFive has existed. Maturity is real, and Internxt has more of it.
Copyleft licensing. Internxt's web and mobile clients are AGPL-3.0, a strong copyleft licence that obliges downstream modifications to stay open (its desktop app, SDK and CLI are MIT). ShieldFive's crypto core is Apache-2.0, which is more permissive. Neither is "better" in the abstract, but if you specifically want copyleft, Internxt's choice fits that preference.
If you want an EU-hosted, open-source, zero-knowledge product that has already been independently tested, Internxt is a strong and honest pick.
Which one fits you
Internxt fits you if you want an EU-based, open-source, zero-knowledge storage product that has already been independently tested and certified, and hybrid Kyber-512 (level 1) protection on account and sharing keys, rather than on file keys, meets your post-quantum requirements — its free tier is 1 GB.
Choose ShieldFive only if its authentication trust boundary, client-specific encryption formats and current assurance limits meet your requirements. Test upload, viewing, sharing and recovery with disposable files before moving important data.
Try it
Test the workflow with disposable files before moving important information. Review the security model, including authentication trust and differences between clients, and check current plans. Internxt and ShieldFive both sell pay-once plans; lifetime cloud storage compared puts them next to the others still on sale.
This comparison reflects each vendor's public documentation as of 22 September 2026 and will be updated as the products change.